How to Create and Upload a Custom Skill in Claude

Claude Skills are reusable folders of instructions, scripts, and reference material that Claude loads when a task matches the skill's description. A custom Skill is useful when you want the same process, quality checks, terminology, or output format applied repeatedly without copying a long prompt into every chat.

The current upload workflow uses a ZIP file containing a skill folder. Uploading a single arbitrary Markdown file is not the supported structure. The folder must contain a file named SKILL.md; it can also include supporting files when the workflow needs them.

Claude Skill folder structure

brand-review/
├── SKILL.md
├── references/
│   └── style-guide.md
└── examples/
    └── approved-copy.md

Keep the folder focused. Put the instructions Claude needs every time in SKILL.md, and move lengthy policies, examples, or templates into clearly named supporting files.

Create the SKILL.md file

A simple Skill can start with YAML front matter followed by direct instructions:

---
name: brand-review
description: Review marketing copy for brand voice, terminology, and required quality checks.
---

# Brand review workflow

1. Read the supplied copy and identify its audience and purpose.
2. Check it against references/style-guide.md.
3. Flag unsupported claims and inconsistent terminology.
4. Return a revised draft followed by a short change log.
5. Do not invent product facts. Ask for a source when a required claim cannot be verified.

The description is especially important because it helps Claude decide when the Skill is relevant. State what the Skill does and the kinds of requests that should trigger it. Avoid vague descriptions such as “helps with work.”

Package and upload the Skill

1. Save SKILL.md as UTF-8 text inside the skill folder.
2. Add only the supporting files the workflow actually needs.
3. Compress the folder as a ZIP file. When extracted, the ZIP should contain the skill folder with SKILL.md inside it.
4. In Claude, open Customize > Skills.
5. Select the + button, choose Create skill, then choose Upload a skill.
6. Upload the ZIP file and enable the Skill.

Menu labels can change, and organization-managed accounts may restrict who can upload or enable custom Skills. Administrators can provision approved Skills centrally for an organization.

Test whether Claude loads the Skill correctly

1. Start a fresh chat and send several prompts that clearly match the Skill description.
2. Confirm that Claude loads the Skill and follows its required sequence, format, and boundaries.
3. Try nearby prompts that should not trigger it. If the Skill loads too broadly, narrow the description.
4. Test missing files, conflicting instructions, malformed input, and high-risk requests.
5. Revise the Skill, increment your internal version note, repackage it, and test again.

A Skill does not guarantee correct output. Keep factual verification, permission checks, and human approval in the workflow when errors could affect customers, systems, money, security, health, or legal obligations.

Security checks before installing a Skill

• Read every instruction, script, and reference file in the ZIP.
• Do not install a Skill that requests credentials, disables safeguards, or sends data to an unexplained service.
• Use organization-approved sources and remove secrets or personal data from examples.
• If scripts are included, review what they read, write, execute, and transmit.
• Test third-party Skills in a low-risk workspace before allowing access to sensitive files or tools.

Claude chat Skills and Claude Code Skills are related but installed differently

In Claude's chat interface, custom Skills are uploaded from Customize > Skills as a ZIP package. In Claude Code, a project Skill normally lives in .claude/skills/<skill-name>/SKILL.md. Use the installation method documented for the product surface where the Skill will run.

Anthropic's current guides explain how to upload and use custom Skills, create a Skill, and manage Skills in Claude Code.

Related TipsMake guides: set up Claude Projects and compare Claude Code Skills and plugins.